Electrical connector grounding apparatus



June 1964 F. EHRMAN ETAL 3,136,593

ELECTRICAL CONNECTOR GROUNDING APPARATUS Filed May 31, 1962 Fig. 5 Fig.6

IN VEN TORS Edward F. Ehrman Frederick J. .Sparber United States Patent3,136,593 nrncrnrcar. CoNNnc'ron onounnnvo Arranarbs The presentinvention relates generally to electrical conductors and connectors andmore particularly to a device which is adapted to insure propergrounding through a connector body when mating electrical conductors.

Electrical connectors normally comprise a pair of mating portions joinedwith conductors and in many instances the mating portions comprise aplug and a receptacle with the latter being provided with an annulargroove adapted to receive an annular barrel member on the plug portion.As the barrel enters the groove current conducting contacts within thebarrel are adapted to engage and mate with a like number of contacts inthe receptacle portion so as to establish electrical flow through theconnector to a point of use. A key-way in one part and a key on theother part may be provided to correctly orient the contacts. Theaccepted manufacturing tolerances for the plug and receptacle portionsare such that the space etween the outer diameter of the barrel memberand the inner diameter of the receptacle may vary a few thousandths ofan inch to several thousandths of an inch from the desired diameter.Thus in many instances when the barrel member is first received in theannular groove there may be a very loose and relatively non-contactingrelationship therebetween so as to provide little or no electricalgrounding or shielding through the connector body. Under normalcircumstances such a loose fit may not be detrimental or interfere withthe normal operation of the connector or with the electrically operatedcomponents being coupled through the connector; however, in the presenceof an electromagnetic field such as radio frequency energy such a loosefit may be highly undesirable since if the plug and receptacle are notproperly contacted or grounded prior to engagement of the currentcarrying contacts the electromagnetic field may cause a discharge tooccur through the contacts and damage electrical circuitry or effect theoperation of electrical components prematurely or in an undesiredmanner.

It has been found that where electromagnetic field generating means arepresent, such as, for example, radar, which produces radio frequencyenergy, that high and low potentials between various components orsystems frequently exist in the area of the field. Thus, if it isdesired to electrically couple through a suitable connector a pair ofcomponents or systems which may be at different potentials, precautionsmust be taken to thoroughly ground such components or systems to thesame potential prior to engagement of the contacts and thereby avoid thedeleterious eifects of the electromagnetic field causing a dischargethrough the contacts of the connector as described above. It istherefore a principal object of the present invention to provide animproved device in combination with electrical conductors or connectorswhich are capable of providing proper grounding between components orsystems prior to engagement of electrical contacts.

Another object of the present inevntion is to provide a new and improvedgrounding device of relatively simple and inexpensive construction.

Another object of the present invention is to provide on one part of anelectrical connector a pluralityof improved finger-like spring segmentswith projections adja- Patented June 9, 1964 cent one end thereof andutilize such projections for contacting another part of the connectorand provide the desired grounding.

A further object of the present invention is to provide an improvedconnector grounding device capable of contacting a receptacle portionabout substantially the entire periphery thereof.

A still further object is to provide lip means for maintainingcontacting spring segments in pre-stressed and correctly orientedpositions.

Other and further objects of the invention will be obvious upon anunderstanding of the illustrative embodiment about to be described, orwill be indicated in the appended claim, and various advantages notreferred to herein will occur to one skilled in the art upon employmentof the invention in practice.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description. The preferred embodiment illustrated isnot intended to be exhaustive nor to limit the invention to the preciseform disclosed. It is chosen and described in order to best explain theprinciples of the invention and their application in practical use tothereby enable others skilled in the art to best utilize the inventionin various embodiments and modifications as are best adapted to theparticular use contemplated.

In the accompanying drawing:

FIG. 1 is a side elevation view, partly cut away, showing a connectorpart embodying the present invention;

FIG. 2 is a front elevation view of the part shown in FIG. 1;

FIG. 3 is a longitudinal sectional view taken along line 33 of FIG. 2,together with a longitudinal sectional view showing a typicalcooperating connector part;

FIG. 4 is an enlarged fragmentary view similar to a portion of FIG. 3showing the contact between the grounding elements and the inner surfaceof a receptacle;

FIG. 5 is an enlarged fragmentary View showing a grounding springsegment in greater detail; and

FIG. 6 is an enlarged fragmentary view similar to FIG. 5 but showing aslightly diiferent spring segment arrangement.

The present invention is illustrated in the drawings embodied, by way ofexample, in the plug portion of a mating plug and receptacle electricalconnector. The plug portion as best shown in FIGS. 1-3 may comprise anannular shell or barrel member or part 11 having a shoulder 12 about itsperiphery intermediate the ends thereof and a contact carryinginsulating insert 13 therein. The barrel part ll may be provided with athreaded outer surface 14 adjacent one end thereof for facilitating theengagement of a cable attaching device or the like (not shown) whileadjacent the other or distal end 15 of the plug barrel 11 there may bestepped recesses 16 and 17 (FIG. 5) provided in the outer surface of thebarrel for retaining grounding elements 18 as will be described indetail below. The term annular as used herein with reference to theshapes of various connector components is not intended to be limited toring-like configurations but is used. in the sense of encompassing allspace enclosing configurations such as round, square, rectangular, etc.

The stepped recesses 16 and 1'7 in the barrel 11 may be formed ormachined in any suitable manner, such as, for example, by a lathe or thelike, so that recess 16 which has the deeper or innermost surfaceextends from a point on the barrel adjacent to the shoulder 12 to apoint immediately adjacent the forward or distal end 15 of the barrel11. The recess 16, which may have a surface generally parallel to thesurface of the barrel 11, may be undercut into the barrel 11 adjacentthe for- 3 ward end in such a manner that a recess-overlying portion orlip 21) is formed. The recess 17, which may have an inner surfacesomewhat shallower and generally parallel to the surface of recess 16(FIG. 5), may be out into the barrel intermediate the shoulder 12 andthe recess 16 in such a manner that the surface of recess 17communicates with the recess 16. Since the recesses 16 and 17 may extendthrough a substantial thickness of the barrel member 11 it may bedesirable to make the barrel 11 from a relatively strong electricalconducting -material such as stainless steel or the like to insure thatthe recesses do not overly weaken the barrel so as to impair its normalmating function.

The grounding elements 18, as best shown in FIGS.

1 and 5 may comprise a plurality of finger-like spring segments 21 whichare adapted to be secured to the barrel against the surface of therecess 17 so as to bridge or extend in a cantilevered fashionsubstantially across the recess 16 so that the free ends thereof mayabut against the underside of the lip 20. The spring-fingers or springsegments 21 may be conveniently formed from a single piece of thin,relatively rigid sheet material, having good electrical conductingproperties, such as, for example, stainless steel or beryllium-copper.The sheet material may be machined or in any other suitable mannerprovided with a plurality of slots or grooves 22 which communicate withone end of the sheet and axially extend through a substantial portion ofthe width thereof so as to provide a plurality of similar springsegments 21 projecting from a common base 23.

To attach the grounding elements 18 to the barrel 11 so that the distalend of each segment 21 is pre-stressed in an outward direction, thesheet material may be first formed in an annular configuration generallycorrespondingto the shape of the barrel 11, then the distal or free endof each segment 21 may be placed within the recess 16 underneath the lip20 and thereafter the common base 23 may be moved inwardly into therecess 17 and attached to the barrel 11 in any suitable currentconducting manner such as by spot-welding or riveting, as generallyindicated at 24. With the grounding elements 18 so attached to thebarrel 11 the base 23 may be on substantially the same horizontal planeas the lip 20 while the distal ends of the segments 21 are disposedbeneath the lip 20, thus causing the distal ends of the segments tocontinuously tend to spring outwardly in an effort to return to thehorizontal plane common with the base 23.

Desired pre-stressing of the segments 21 may be easily determined bypreselecting the thickness of the lip 21 and the depth of the recess 17.However, the depth of the recess 17 may be normally such that with thebase 23 mounted therein the outer surface of the base 23 hassubstantially the same outer diameter as the lip 20, thus insuring thatno objectionable obstruction which may interfere with the mating of theplug and receptacle connector portion, is present at the point where thebase 23 is attached to the barrel.

To provide an electrical coupling through the connector, the barrel part11 of the plug portion is adapted to be received in an annular groove 25within a mating electrically conducting receptacle portion 26 whichnormally contains an insulating insert 27 having contact elementstherein which are adapted to mate with the contact elements 29 in theplug portion to complete the electrical coupling through the connector.As shown in FIGS. 3 and 4, the contact elements 29 in the plug portionand the contact elements 30 in the receptacle portion are in the form ofpins and sockets respectively; however, it will appear clear that thecontacts 29 or 30 may be in either mating portion. After the barrel 11is received within the groove 25 and the pins 29 engage the sockets 30,the mating portions may be secured together by a barrel encirclingsleeve 31 having an inwardly extending flange adapted to abut theshoulder 12 and which is adapted to mate with a threaded surface on thereceptacle portion 26 for providing a secure connection betwen theconnector portions.

To provide the desired contacting or grounding between the mating partsprior to engagement of the contact elements 29 and 39, each springsegment 21 may be provided with a radially extending projection 32 onthe outer surface and adjacent to the distal or free end thereof. Theseprojections 32 come into positive contact with the receptacle bodysomewhat before the mating of the contacts 29 and 30 to insure that theconnector portions are properly contacted or grounded before theengagement of the contact elements 29 and 39. After contact is madebetween the projections 32 and the leading edge of the receptacle body,a slight axial pressure exerted on either mating portion causes thespring fingers or segments 21 to be moved inwardly a sufficient distanceso as to permit the barrel 11 to enter into the groove 25 and yetmaintain an interference fit with the inner surface of the receptacle(FIG. 4). While the contacting elements 18 are shown in the connectorplug portion it will appear clear that such elements may be provided inthe inner surface of the connector receptacle portion 26.

The thickness or height of each projection 32 should be such that itwill engage the leading edge of a receptacle portion having the maximummanufacturing tolerance or inner diameter. Thus after determining thenecessary height of the projections 32 the depth of the recess 16 may bedetermined so that if the plug portion is used with receptacle portionhaving a minimum manufacturing tolerance or inner diameter theprojections 32 and the spring segments 21 will be able to move inwardlyinto the recess 16 sufficiently to allow the mating of the connectorportions. In FIG. 4 the distal end of a segment 21 is shown abuttingagainst the surface of recess 16; however, it will appear clear that thedistal end of the segments 21 may be at any point between the innersurface of the lip 21) and the surface of recess 16..

While the projections 32 may be integral with or attached to the springsegments 21 in any desired manner and be of any desired shape,satisfactory results have been attained by having the projections 32integral with the spring segments 21 and formed in a generally lobelikeconfiguration with a slightly slanted leading edge 33 for easing themating of the connector portions.

With a connector plug portion embodying the present invention theleading edge 15 of the barrel is solid or unbroken except for theaxially extending slot or keyway 34 (FIG. 3), thus insuring propermating by allowing the technician coupling the connector to seek out akey (not shown) in the receptacle portion prior to placing a load on thespring segments 21. Also by using a plurality of such spring segments 21and projections 32 about the periphery of the plug barrel, grounding iseffected in a more desirable manner in that the projections 32 contactthe receptacle body around substantially its entire annular leading edgeprior to permitting the engagement of the contact elements 29 and 30.This feature of grounding about the entire periphery of the connector isimportant in that the electrical field is capable of causing a dischargethrough the contact elements of the connector even though a portion ofthe connector is already grounded. While eight spring segments andprojections are illustrated in FIG. 3 it will appear clear that anydesired number of such segments and projections may be used.

If it is desired to increase the pressure exerted by the spring segments21 against the inner surface of the receptacle body a slight rearwardslant 36 may be given to the surface of recess 17 (FIG. 6) so as tocause the spring fingers 21 to be more of an arcuate shape and therebyincrease the spring or biased effect of the segments 21.

It will be seen that the apparatus of the present invention sets forth ahighly desirable structure for effecting proper contacting or groundingbetween components or assemblies so as to obviate or substantiallyminimize contacting or grounding problems heretofore known. Providing asubstantially solid or unbroken leading edge and lip on the plugportion, the spring segments are maintained in proper positionalrelationship to each other by preventing deformation of the springsegments by a carelessly inserted or placed screwdriver or test probe.Also, due to the unique relationship of the spring segments to thesubstantially solid leading end, rough handling, such as dropping theconnector and impacting it against a concerete floor or the like, doesnot deform the spring segments so as to prevent proper connectorassembly. Unequal pre-stressing of the segments 21, i.e., where one ormore segments 21 tend to provide a greater spring effect, iscompensatedfor by the overlying lip 20 in that the latter confines the segments topredetermined positions and thus evens out the pre-stressing. The lip 20also assures that segment inaccuracies such as spreading and the likewhich may easily occur when using non-confined individual barrelsegments are obviated because of the novel segment position retainingfeatures provided by the lip 20.

As various changes may be made in the form, construction and arrangementof the parts herein without departing from the spirit and scope of theinvention and without sacrificing any of its advantages, it is to beunderstood that all matter herein is to be interpreted as illustrativeand not in a limiting sense.

We claim:

An electrical connector mating portion having a contacting element andan annular metal grounding shell encircling said element andinsulatively spaced therefrom comprising an axially elongated recessedsurface peripherally disposed about said shell and extending to alocation adjacent one end thereof, another peripherally disposedrecessed surface in said shell communicating with and laterallyoutwardly spaced from the first mentioned recessed surface at a locationremote to said one end, a generally annular retaining lip on said shelladjacent said one end thereof and laterally spaced from and overlying asection of the first mentioned recessed surface, spring means comprisinga base portion disposed against and secured to said other recessedsurface and essentially encircling the shell with an outermost surfaceof said base portion having essentially the same perimetric dimensionsas an outermost surface of said retaining lip, a plurality of axiallydisposed flexible segments spaced about the first mentioned recessedsurface and extending from said base portion in cantilever fashionacross essentially the entire first mentioned recessed surface to alocation beneath said retaining lip with the distal ends of saidsegments being constrained generally laterally inwardly from the baseportion by said retaining lip and thereby effecting the continuousurging of said distal ends towards said retaining lip while resistingmovement towards the first mentioned recessed surface, and a laterallyoutwardly extending projection on each of said segments at a locationadjacent said retaining lip and disposed closer to said one end of theshell than said contacting element for contacting a surface on a metalshell of another mating connector portion prior to the establishment ofan electrical path from said contacting element to a mating contactingelement in said other mating connector portion.

References Cited in the file of this patent UNITED STATES PATENTS2,425,834 Salisbury Aug. 19, 1947 2,704,354 Boerum Mar. 15, 19552,755,331 Melcher July 17, 1956 2,760,177 Hollis et al Aug. 21, 19562,822,418 Dinnick Feb. 4, 1958 3,054,981 Malek et al. Sept. 18, 1962FOREIGN PATENTS 704,450 Germany Mar. 31, 1941 1,025,478 Germany Mar. 6,1958 639,979 Great Britain July 12, 1950 353,783 Switzerland June 15,1961

